Neurons of the motor cortex projecting commonly on the caudate nucleus and the lower brain stem in the cat

The cortico-caudate projections due to collateral axons of cortico-spinal and/or cortico-bulbar fibers were explored. In 34 cats, 59 neurons in the motor cortex were extracellularly identified to be antidromically activated by stimulation of the caudate nucleus (Cd). Thirty four neurons responded antidromically only to Cd-stimulation, and they were irresponsive to thalamic stimulation. Contrarily, 25 neurons responded antidromically not only to Cd-stimulation but also to stimulation of the cerebral peduncle and/or the medullary pyramid. 40% of the latter were orthodromically activated by thalamic stimulations. They were considered to be important in coordinating the cerebellum and the basal ganglia system.